This invention relates to a data scrambler which can prevent a user of a receiver from executing reverse-engineering of received data files and/or from reusing them without the authority. For example, this invention can be applied to a system in which the receiver receives multiple kinds of data files and then processes them to obtain a processed output.
Various data management has been proposed in the art, and a suitable one of them is selectively utilized, corresponding to system environments, or the like. In one environment, it may be often undesirable to handle original data without any changes. In this case, the original data should be separated into a plurality of data files to be managed. In another environment, it is useful to separate original document data into their contents and their formats, and then, to manage them independently.
Such a plurality of data files can be independently transmitted, for example, through the Internet to the receiver or the operator, if management of the files and operation of them are carried out in different spaces from each other. On receiving the files, the receiver combines and processes them to obtain the processed output, like in a formatted document. Such file management provides easy operation to view one content in various formats, to watch various contents in one format, and to modify contents or formats without consideration of formats or contents.
However, if the transmitted data files remain in the original forms, someone may apply reverse-engineering of them and/or may reuse them in unauthorized ways. That is, someone may eavesdrop on the transmitted data files and may partially extract one of the contents from them. And furthermore, the extracted content may be changed into another format different from an original format to be sold to other persons. In such case, it is not easy for the distributor to recognize the cheating and the unauthorized practice, because of a difference between original and sold data formats.
To avoid the cheating and the unauthorized practice, encryption/decryption mechanism, such as the Secure Sockets Layer (SSL), are used in the conventional art. In this event, the transmitter transmits encrypted data files, while the receiver executes decryption to the transmitted data files.
However, this conventional approach has the following problems. Certainly, according to this approach, nobody can execute the undesired practice without the decryption code. It should be however noted here that the receiver always holds the decryption code, and therefore, the approach cannot prevent the transmitted data files from the unauthorized reuse of a user of the receiver. Furthermore, this approach requires a decryption apparatus in the receiver""s side. Such requirement incurs a superfluous cost on the receiver""s side. The tendency goes forward more and more, if the number of the receivers increases. Moreover, once the encryption method is decided in this approach, it is difficult to change the method, because the change requires not only new transmitter device but also new receiver device.
This invention therefore provide a scrambling method of data files which can prevent a user of a receiver from executing undesired practice of received data files. This scrambling method is quite different from the conventional techniques, but may be combined with the techniques.
According to one aspect of this invention, the following method of scrambling original data files into scrambled data files is obtained. On receiving such the scrambled data files, a destination node carries out predetermined processing of the scrambled data files.
The method comprises converting the original data files into converted data files different from the original data files, respectively. Specifically, the converted data files are selected or determined, such that the destination node obtains the same processed output when the converted data files are subjected to the predetermined processing. Therefore, the destination node, such as a receiver, does not need a specific arrangement to process only the converted data files, but does a processor capable of processing the original data files.
Such method further comprises transmitting the converted data files as the scrambled data files to the destination node. Herein, the converted data files may be directly transmitted as the scrambled data files. Prior to the transmitting, the converted data files may be further subjected to encryption.